Traditionally, fluid production systems on subsea hydrocarbon wells have been powered by hydraulics fed from a high-pressure source on a surface vessel or platform via expensive umbilical tubing. The historical reason for this is that hydraulic systems were seen to be very reliable compared to electrical systems, mainly because the required electric devices, both actuating and control, such as motors and relays, were considered to be much less reliable than hydraulic equivalents.
However, with recent developments in electric motors and electrically powered actuators for the subsea environment and the maturity of solid state power switching devices, such as solid state relays, the simplicity of electrical systems is becoming attractive to the subsea fluid extraction business, both from the point of view of costs and reliability.
The use of electrically powered techniques in subsea fluid extraction is disclosed, for example, in GB-A-2 328 492, GB-A-2 332 220 and GB-A-2 350 659 and UK Patent Applications Nos. 0128924.8 and 0131115.8.